Copper conductor for electric-lamp bulbs and other vacuum tubes



T. YANAI. COPPER CONDUCTOR FOR ELECTRIC LAMP BULBS AND OTHER VACUUMTUBES.

APPLICQHON FILD MAY 29, I918- 1,417,387.

Patented my23,1922.

v v E/v ag; I a), 7 ez 20 yazaz: V I

ATTY- I in glass rods and UNITED STATES PATENT OFFICE.

TEIZO YANAI, OF TOKYO, JAPAN, ASSIGNOR TO NIHON DENKI KOGIJ'O KABUSHIKIKAISHA, OF TOKYO, JAPAN.

COPPER CONDUCTOR FOR ELECTRIC-LAMP BULBS AND OTHER VACUUM TUBES.

Application filed May 29,

Tokyo, Japan, have invented new and use ful Improvements in CopperConductors for Electric-Lamp Bulbs and Other Vacuum Tubes, of which thefollowing is a specification.

This invention relates to leading-in conductors of electric lamp bulbsand the like, which consists of slender copper tubes sealed to a processof forming such conductors. The object of this invention is to obtain acheap substitute for platinum which is usually employed for the purpose,by the use of a copper conductor which is made hollow, the conductorbeing thus made somewhat flexible and crevices being prevented fromappearing between the conductor and the glass rod in which it is sealed,due to difference of the coefiicient of expansion of copper and glass.

In the accompanying drawings, Fig. 1 shows a tube formed by windmg orbending a long thin skelprof copper, and Fig. 2 shows copper tubessealed in a glass rod in accordance with this invention.

Hitherto there have. been incandescent electric lamps and other vacuumtubes with leading-in conductors of copper, but in such bulbs and vacuumtubes, although the surface of the conductors and the glass rods tightlystick together, there a drawback of their not perfectly maintainingvacuum, crevices being formed, "when subjected to changes of temperaturebetween the copper wire and the glass rod due to the difference ofcoeflicients of expansion of the two. The present invention is animprovement on the above, and consists in the use of copper wire whichis made hollow, thus a certain degree of flexibility being given theretoand the separation of the wire from the glass being effectivelyprevented notwithstanding the strain caused between the two whensubjected to change of temperature due to differences in theircoefficients of expansion.

The following is an example of one man- Specification of Letters Patent.

Patented May 23, 1922.

1918. Serial No. 237,183.

nor in which my invention may be put into prac-tlce Take a thin copperwire and press part of 1t fiat and thin by a roller or any othersuitable means. Bend this flattened part 1nto a tube, joining the edge(1) with the edge (2), as shown in Fig. 1, and leaving vacant place (3)within. A conducting wire 6 formed of any suitable material is nowinserted into the tubular portion, whereupon the front end 5 thereof ispressed toward the wire 6 so that the tubular portion is closed. Thetube and wire are now inserted into the glass wall of the bulb,whereupon the glass is subsequently heated to a semimelted condition.The heating is continued for a while and the glass rodis pressed flat asfar as the hollowness of the copper tube is not interfered with. Thusthe copper tube is hermetically sealed, and a glass rod with hollowspace within, which hollow space being surrounded by copper, is formed.

I am aware that before this invention there is known a leading-in wireof metal tube used with vacuum containers such as vapor lamps or vaporrectifiers through which a large amount of electric current passes; butsuch leading-in wire cannot practically be used with ordinaryincandescent lamp bulbs. Now, according to my invention, a'copper tubeis formed by bending one edge of a thin narrow strip of that metal overthe other edge, and a very slender tube can very easily be formed bysimply passing a very narrow thin strip through'a die.

I claim A leading-in conductor for vacuum containers comprising a singlelength of material having a slit tube formed integral therewith at oneend thereof, the longitudinal edges of said tube overlapping, and a wireclosing the open end of the tube. y

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

TEIZO YANAI.

Witnesses:

' H. F. ALTMANs, YOSHIO lKAWADA.

